**4. Discussion**

*Protected Areas, National Parks and Sustainable Future*

3 years (2003) (Seed year: 2003)

5 years (2001) (Seed year: 2003)

**Eastern white pine Balsam fir**

*Comparison of living sapling and seedling densities (after burning) of Eastern white pine and balsam fir in* 

5 10 15 20 25 30 35 40 45 50

3 years (2003)

5 years (2001)

7 years (1999)

9 years (1997)

11 years (1995)

5 10 15 20 25 30 35 40 45 50

5 10 15 20 25 30 35 40 45 50

5 10 15 20 25 30 35 40 45 50

5 10 15 20 25 30 35 40 45 50

5 10 15 20 25 30 35 40 45 50

*burned (n = 5; 2004–2005 excluded) and unburned sites (n = 9).*

5 10 15 20 25 30 35 40 45 50

5 10 15 20 25 30 35 40 45 50

5 10 15 20 25 30 35 40 45 50

5 10 15 20 25 30 35 40 45 50

7 years (1999) (Seed year: 2003)

9 years (1997) (Seed years: 1998, 2003)

11 years (1995) (Seed years: 1995, 1998, 2003)

**46**

**Figure 5.**

**r e**

**of s**

**e**

**es**

**gnil d**

**p**

**ehr e**

 **er at c**

**Table 3.**

**b**

**muN**

**Height of seedlings (cm)**

*Distribution of eastern white pine and balsam fir seedlings among 5-cm height classes in burned stands of various ages in La Mauricie National Park of Canada. No eastern white pine seedling exceeded 45 cm of height.*

Prescribed burnings carried out in La Mauricie National Park of Canada killed 38 and 67% of competing balsam trees and saplings respectively and increased eastern white pine seedling density up to an average of 21,133 seedlings/ha, compared with 5135 seedlings/ha in unburned stands. This is higher than the 12,000 seedlings/ ha reported 5 years after small scale (0.2 ha) prescribed burning trial done in an eastern white pine stand at the Petawawa forest research station located in Ontario [41]. Stands burned in 2004 and 2005 had very low density of eastern white pine seedlings when compared with other burned stands because no seed crop occurred after the treatment was applied and the time of our study. However, in these stands, the bracken fern species (*P. aquilinum*) was abundant with an average cover of 26%*.* This fern is highly competitive in recolonizing burned stands when it is present prior to treatment. It is a fire-adapted species that possesses deep fire-resistant rhizomes [50]. Bracken ferns are strong competitors for light and their presence is known to increase the level of competition for the establishment of eastern white pine seedlings [13]. In the future, after a first good seed crop, it would be important to monitor and measure the regeneration of eastern white pine and the effect of the abundance of this fern on pine dynamics. The production of a good seed crop is important after fire or a burning treatment in order to establish strong pine regeneration. Moreover, the succession of various events may also be favourable to establish pine regeneration as described by Lynham and Curran [51]. They reported 50,000 red and white pine seedlings per hectare 5 years after a low-intensity natural fire followed by a good seed crop 2 years later and a blowdown 4 years after the fire. This generated optimal conditions for regenerating pines. Such condition may explain why one of our unburned stand, which was located on an island, had a high density of eastern white pine saplings (100/ha) even though its seedling density was rather low (625/ha). This stand had been disturbed by a small blowdown due to its location on an island. Gaps produced in the forest cover were large enough to favour the growth of eastern white pine seedlings up to the sapling stage. This is important for eastern white pine forest renewal as Stiell [52] demonstrated that pine's ability to compete is greatly improved when the sapling stage is reached. However, even if all the saplings recorded in our unburned stands would reach the canopy, their numbers would still remain below the density objective of 100/ha [40].

The stands burned in 2001 and 2003 benefited from a good seed crop in 2003 and they had numerous seedlings, approximating 20,000 seedlings/ha. Most pine seedlings were grouped in the 5- to 10-cm height class and showed a normal growth rate for eastern white pine [13]. The stand burned in 1999 was submitted to the highest fire intensity and showed the highest recent mortality of trees, including some pines. It also produced taller eastern white pine seedlings than the site burned 2 years before. No competing vegetation reinvaded this stand and the good 2003 seed crop allowed regenerating eastern white pine, even if it occurred only 4 years after the treatment. Furthermore, the taller seedlings observed indicate better growth conditions in this stand. This could be linked not only with better soil conditions but also with a higher penetration of light due to higher tree and sapling mortality. Finally, the tallest eastern white pine seedlings were observed in the oldest burned site, but these only reached 50 cm of height, which shows a slow growth rate after 11 years [13].

## **5. Conclusions**

Active management is an important approach for restoring the ecological integrity of ecosystems in Canadian national parks. The current policy states that when park ecosystems have been seriously altered by human activities and natural processes cannot achieve restoration objectives alone, intervention may be prescribed. In La Mauricie National Park of Canada, the ecological integrity of eastern white pine forest ecosystems has been altered by logging, fire suppression, and the introduction of the exotic white pine blister rust. On a short-time scale (10– 15 years), the prescribed burning programme implemented in the park has been successful in increasing eastern white pine seedling density significantly. However, in the near future, it would be important to continue monitoring each burned stand to make sure that local environmental conditions remain favourable for the growth of eastern white pine seedlings. Initial growth of eastern white pine usually averages 10–15 cm after 5 years [13], which is slow compared with faster growing competitors such as firs and hardwoods. In order to evaluate the ecological integrity of a national park, Timko and Innes [53] recently recommended such monitoring for assisting managers in evaluating the effectiveness of their management actions.

According to Ontario Ministry of Natural Resources [54], eastern white pine seedlings that receive more than 45% of full light have a higher probability of reaching the sapling stage. Otherwise, seedlings will probably survive but might not be able to grow rapidly enough to outcompete firs and broadleaved species. Waldrop and Brose [31] have shown that low-intensity prescribed burnings in Ponderosa pine stands do not open sufficiently the overstory strata to ensure survival and fast growth of seedlings established after treatment. In such cases, it might be necessary to use further treatment to reach the objective of restoring pine forest ecosystems. It might be the case in burned stands of La Mauricie National Park of Canada as densities of eastern white pine seedlings are high, but their growth appears rather slow. Eastern white pine seedlings may benefit from opening the canopy to increase light penetration. In Ponderosa pine stands, it has been shown that thinning was more effective than burning to open the overstory and kill a higher proportion of mature trees [33, 34]. These authors concluded that the combination of thinning and burning was the most effective option for optimizing light penetration and ensuring good seedling growth. In eastern white pine stands of La Mauricie National Park of Canada, we may hypothesize that this objective could be achieved by girdling mature balsam fir or spruce trees or by increasing fire intensity in future prescribed burnings. Girdling appears as a better option than thinning for a national Park as it leaves

**49**

provided the original work is properly cited.

1 Natural Resources Canada, Québec, Canada

2 Université Laval, Québec, Canada

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*, Éric Domaine2,3 and Louis Bélanger2

3 Ministère des Forêts, de la Faune et des Parcs, Québec, Canada

\*Address all correspondence to: christian.hebert@canada.ca

*Prescribed Burning to Restore Eastern White Pine Forests of La Mauricie National Park…*

and ensure that decision-making is based on sound science [55].

large diameter snags on site which increases the treatment value with respect to the concept of ecological integrity. Prescribed burning effectiveness for killing mature trees can be enhanced by increasing fire intensity but, this also increases risks of escaping the fire, which represents a fragile equilibrium between the ecological value of the treatment and safety rules [34]. Nevertheless, continuous monitoring of seedling growth in burned stands would help managers to confirm that such management practices are useful in La Mauricie National Park of Canada to restore eastern white pine ecosystems. These evaluations would also promote adaptive management

We thank Yves Dubuc from Natural Resources Canada as well as the summer students Jennifer Naples, Félix-Antoine Boucher, Jonathan Boucher, Éloïse Laurier, and Vincent Mandon for their help with field work. We also acknowledge Victor Kafka, Raymond Quenneville, and Michel Thériault from Parks Canada for their

Financial support to run this project was provided by Parks Canada and Natural

*DOI: http://dx.doi.org/10.5772/intechopen.86224*

**Acknowledgements**

logistical support.

Resources Canada.

**Author details**

Christian Hébert1

**Funding**

*Prescribed Burning to Restore Eastern White Pine Forests of La Mauricie National Park… DOI: http://dx.doi.org/10.5772/intechopen.86224*

large diameter snags on site which increases the treatment value with respect to the concept of ecological integrity. Prescribed burning effectiveness for killing mature trees can be enhanced by increasing fire intensity but, this also increases risks of escaping the fire, which represents a fragile equilibrium between the ecological value of the treatment and safety rules [34]. Nevertheless, continuous monitoring of seedling growth in burned stands would help managers to confirm that such management practices are useful in La Mauricie National Park of Canada to restore eastern white pine ecosystems. These evaluations would also promote adaptive management and ensure that decision-making is based on sound science [55].
